Hi GUys
Enzymes are Asthma sensitisers and it's the dust that causes problems.
So you spray on carpet, extract most of it, what is left dries and breaks up into tiny dust particles which in sensitive people can cause Asthma attacks.
Another thing about enzymes is that they are catalysts, that is they do not form part of the chemical reaction but act in a way to speed it up and in some cases make it posssible, which all means a very small amount of enzyme can cause severe problems.
Cheers
Doug